333
JOHNSON CONTROLS
FORM 201.21-NM3 (616)
PROBLEM
POSSIBLE CAUSE
ACTION
System Fault:
HIGH
DISCHARGE
PRESSURE
Coils dirty.
Check and clean coils.
Coils are damaged.
Comb out fins.
Fans NOT operating.
Check fan fuses.
Check fan rotation.
Check fan motor/blade.
System is overcharged.
Remove charge and check subcooling.
System Fault:
HIGH
DISCHARGE
TEMPERATURE
Discharge Temperature
Sensor is defective.
Check Sensor.
Condensor Fans NOT operating
or are running backwards.
Check Fans.
Coils dirty.
Check and clean Coils.
High Superheat.
Measure Superheat with gauges and
thermocouple. Determine cause.
System Fault:
HIGH MOTOR
TEMPERATURE
High Motor temperature
input from one of the sensors
Refrigerant charge low.
Check subcooling.
Excess charge in system,
High discharge pressure.
Check subcooling.
High Superheat. Drain/Feed Valves
NOT controlling. Isolate cause.
Motor Sensor reading incorrectly.
Program panel to ignore
a single sensor.
Economizer Solenoid energized at
low speeds. Valve is leaking through.
System Fault:
LOW
SUCTION
PRESSURE
Low charge.
Check subcooling.
Transducer reads incorrectly.
Check transducer against a gauge.
Suction Temp. Sensor
reads incorrectly.
Check sensor against
a thermocouple.
Low flow.
Check flow.
Feed or Drain Valve NOT operating
Check Feed and Drain Valve
operation.
Check superheat.
Feed or Drain Valve defective.
Check Feed and Drain Valve
operation.
Check superheat.
System Fault:
DISCHARGE
PRESSURE
LIMITING
Discharge Transducer is defective.
Check transducer against a gauge.
Ambient Temp. very high.
Normal operation.
Fans NOT operating.
Check fan operation.
Remote or local discharge pressure
load limiting is programmed.
Normal operation.
TROUBLESHOOTING GUIDE (CON'T)
99
(Always remove power to the chiller and assure the DC bus voltage has bled off)
Summary of Contents for YCAV0267E
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Page 348: ...348 JOHNSON CONTROLS FORM 201 21 NM3 616 MAINTENANCE NOTES ...
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